Enkephalins and other opioid peptides (such as beta-endorphin) which contain enkephalin sequences represent an important class of analgesics which occur naturally in animals. Although research over the past 4 years has focused on enkephalins found in the brain, there is now good evidence for the production in the adrenal gland of a new class of opioid peptides and beta-endorphin of the pituitary. The overall objectives of this research are (1) to perform structural studies by microsequence analysis of the adrenal opioid peptides, (2) to chemically synthesize peptides corresponding to enkephalin sequences located within the opioid peptides, and peptides corresponding to nonenkephalin subregions of the opioid peptides, (3) to use the synthetic peptides to elicit classical and/or monoclonal antibodies which specifically recognize internal enkephalin sequences or sequences corresponding to subregions between enkephalin sequences, (4) to develop immunoassays for these peptides based on labeled synthetic peptides and their corresponding antisera, and (5) to use th synthetic peptides, the antisera, and immunoassays to determine the distribution and processing of these opioid peptides, and as probes of the opioid peptide receptors and mode of action as analgesic agents. The synthesis and coupling of peptides to protein carriers for antibody production will be performed using improved methodology developed in this laboratory. Biochemical, histological, and physiological studies will be performed in collaboration with Drs. Udenfriend and Stein at the Roche Institute for Molecular Biology.